Start with soil, not the bed itself

The bed is just a container. What matters is the soil inside it. Fill your raised bed with a mix of topsoil, compost, and peat moss or coconut coir in roughly equal parts. This blend drains well enough that roots won't rot, holds enough moisture that you won't water constantly, and gives vegetables the nutrients they need for the first month or two.

Do not use garden soil from your yard—it compacts in a raised bed and blocks drainage. Buy bagged soil from a garden center or hardware store, or have it delivered if your bed is large. A 4-by-8-foot bed that is 12 inches deep needs about 32 cubic feet of soil, which is roughly 16 bags of standard potting mix.

Fill the bed completely and water it the day before you plant. The soil will settle slightly, and the moisture helps seeds and seedlings make contact with the earth around them.

Key Takeaways

  • Use a soil blend of topsoil, compost, and peat moss or coir in equal parts, not garden soil from your yard.
  • Space vegetables according to their mature size, not their current size—a seedling that looks small will grow to fill its space.
  • Plant seeds directly in the bed for fast-growing crops like lettuce and beans; start seedlings indoors for tomatoes, peppers, and eggplant if your growing season is short.
  • Water the soil, not the leaves, and do it in early morning or late afternoon to reduce disease and water loss.
  • Add compost or aged manure to the top 2 inches of soil each spring to replace nutrients that vegetables consumed the year before.

Decide whether to plant seeds or seedlings

Some vegetables grow so fast from seed that starting them indoors makes no sense. Lettuce, spinach, radishes, beans, peas, carrots, and squash all sprout quickly and reach harvest in 30 to 70 days. Plant these seeds directly in the raised bed at the depth listed on the packet—usually one-quarter to one-half inch for small seeds, one inch for larger ones.

Other vegetables take so long to reach maturity that you need a head start. Tomatoes, peppers, eggplant, and cabbage take 60 to 90 days from transplant to harvest. If your growing season is shorter than that, start these from seedlings indoors 6 to 8 weeks before your last frost date, then move them to the bed once the soil has warmed and frost danger has passed. Check your local frost date with your county extension office or a straightforward online search for your zip code.

Seedlings are also the practical choice if you do not have the space or light to start seeds indoors. Buy them from a garden center in spring—they cost a few dollars each and eliminate the guesswork.

Space plants according to their full size

The biggest mistake new gardeners make is planting too close together. A tomato seedling looks tiny next to a lettuce plant, but it will grow 4 to 6 feet tall and 2 to 3 feet wide. Crowding leads to poor air circulation, disease, and smaller harvests.

Check the seed packet or seedling label for the mature width of each plant. Tomatoes need 24 to 36 inches between plants. Peppers need 18 to 24 inches. Lettuce and spinach need 6 to 12 inches. Squash and cucumber need 24 to 36 inches. Space them as if they are already full-grown, even though they look like they are not.

In a 4-by-8-foot bed, you might fit two tomato plants, four pepper plants, and a row of lettuce along the edge. In the same bed, you could fit one large squash plant and little else. Plan your layout on paper before you plant so you do not crowd things and have to dig them up later.

Plant at the right depth and water when ready

Most seeds should be planted at a depth equal to two or three times their width. A tiny lettuce seed goes one-quarter inch deep. A bean seed goes one inch deep. Press the seed gently into the soil with your finger, cover it, and water with a fine mist so you do not wash it away.

Seedlings go in at the same depth they were growing in their container, with one exception: tomatoes can be planted deeper, up to their first true leaves. Bury the lower stem of a tomato seedling and it will grow roots all along the buried stem, making a stronger plant.

Water the soil when ready after planting, and keep it consistently moist (not soggy) for the first two weeks while seeds germinate or seedlings establish roots. After that, water deeply but less often—usually once or twice a week depending on heat and rainfall. Water the soil at the base of the plant, not the leaves, to prevent fungal disease. Early morning is the best time because the leaves dry quickly as the sun rises.

Thin seedlings and remove weeds early

If you planted seeds directly in the bed, they will sprout close together. Once they have two true leaves (the second set to appear, which look like the adult plant), thin them by pulling out the weaker seedlings and leaving only the strongest one at the spacing you planned. This feels wasteful, but crowded seedlings will all be stunted.

Pull weeds by hand as soon as you see them, when they are small and the soil is moist. A weed that has been in the bed for a month will have a deep root and will break off when you pull it, leaving the root behind to regrow. Weeds compete with vegetables for water and nutrients, so removing them early saves you work later.

Mulch the soil surface with one to two inches of straw or shredded leaves once plants are established. This keeps weeds from sprouting, holds moisture in the soil, and keeps the soil cooler during hot weather.

Feed plants as they grow

The soil you mixed at the start will feed your vegetables for the first month or so. After that, they need more. Use a balanced fertilizer—something labeled 10-10-10 or 5-5-5—mixed at half strength and applied every two weeks. Or side-dress plants with compost: pull back the mulch, scatter a one-inch layer of compost around the base of each plant (not touching the stem), and pull the mulch back over it.

Tomatoes and peppers benefit from extra calcium once they start flowering, which prevents blossom-end rot (a dark, sunken spot on the fruit). Crush eggshells and scatter them around the base, or use a fertilizer labeled for tomatoes. Leafy greens like lettuce and spinach need more nitrogen than fruiting plants, so feed them every 10 days if you want them to grow fast.

Harvest regularly to encourage more growth

Pick lettuce, spinach, and other greens as soon as they are large enough to eat. The more you harvest, the more the plant produces. Pinch off the top inch of basil and other herbs to make them bushy instead of tall and leggy.

Pick tomatoes and peppers when they reach full size and color. Leaving ripe fruit on the plant signals the plant to stop flowering and producing new fruit, so removing it keeps the harvest coming. Pick beans and peas while they are still tender—waiting for them to mature fully slows down new pod production.

At the end of the season, pull out dead plants and add them to a compost pile or yard waste bin. Leave the roots in the soil—they will break down and add organic matter. Spread two to three inches of compost over the bed in fall or early spring, and your raised bed will be ready for the next year.

Frequently Asked Questions

Can I plant vegetables in a raised bed in fall?

Yes. Cool-season crops like lettuce, spinach, kale, broccoli, and cabbage grow well in fall and even into winter in many regions. Plant them 8 to 10 weeks before your first expected frost so they have time to mature before hard freezes arrive. Spring planting is more forgiving because temperatures are rising, but fall crops often taste better because cool weather slows growth and concentrates sugars.

How often should I water a raised bed?

It depends on heat, rainfall, and soil type. In hot weather, a raised bed may need water every day. In cool weather with rain, it may need water only once a week. Stick your finger two inches into the soil; if it feels dry, water. If it feels moist, wait. Drip irrigation or soaker hoses deliver water slowly and directly to roots, reducing waste and disease compared to overhead watering.

What if my raised bed is in partial shade?

Leafy greens, herbs, and root vegetables tolerate partial shade (4 to 6 hours of sun). Tomatoes, peppers, squash, and beans need full sun (6 to 8 hours or more). If your bed gets less than 4 hours of sun, focus on shade-tolerant crops like lettuce, spinach, kale, and parsley. You will harvest less, but you will still harvest.

Do I need to replace all the soil each year?

No. Add two to three inches of compost or aged manure to the top of the bed each spring, and mix it into the top few inches of existing soil. This replaces nutrients that vegetables consumed and adds organic matter that improves drainage and water retention. After several years, the original soil will have broken down and been replaced, but you do not need to empty the bed and start over.

Can I plant the same vegetable in the same spot every year?

It is better not to. Planting the same crop in the same spot year after year depletes specific nutrients and allows pests and diseases to build up in the soil. Rotate crops: if tomatoes grew in one section this year, plant beans or lettuce there next year. Beans add nitrogen to the soil, which tomatoes will use the following year. This practice, called crop rotation, keeps soil healthy and reduces pest problems without chemicals.